Assessing impact sound insulation in floating floors assembled from Construction and Demolition Waste

In the realm of civil construction, there is an increasing demand for sustainable technological advancements aimed at improving the technical quality and comfort of buildings. This shift in perspective has generated heightened interest in innovative solutions that positively influence a building's acoustic performance. This research is dedicated to developing unique floor screed systems utilizing Construction and Demolition Waste (CDW). The evaluation specifically focuses on their impact on noise levels within construction systems, aligning with current standards. The primary goal is to measure the normalized impact sound pressure level (L_n) in various flooring systems within individual units. To achieve this, 30 square-meter samples were designed to create alternative flooring systems using CDW, incorporating materials such as rubber chips, expanded clay, and an air-entraining additive. Common floor coverings, including ceramic, porcelain, wood laminate, vinyl, and granite, were applied over these cementitious screeds. In addition to L_n measurements, the proposed floor screeds underwent impact sound insulation calculations within CYPE AcouBAT software, utilizing a 3D model representing a typical Brazilian residential building. The findings indicated that all flooring systems employing alternative materials demonstrated acoustic performance comparable to traditional construction solutions. The most favorable outcomes were observed with mortar having a mix ratio of 1 : 1.25 : 0.64 : 0.20 : 0.91 (cement : CDW sand : natural sand : expanded clay : water-binder ratio) in weight units, achieving a compressive strength of about 14.5 MPa with a weighted reduction of impact sound pressure level (ΔL_w) equal to 23 without covering and 32 with a glued laminated flooring. Simulated weighted normalized impact sound pressure level in the field (L_nT,w ^′ ) reached 47 dB within the typical building, falling below the recommendation set by the National standard for a superior level (≤ 55 dB). In addition to their soundproofing capabilities, these custom-designed flooring systems offer substantial environmental advantages by repurposing CDW.